/* ----------------------------------------------------------------------
* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
*
* $Date:        19. March 2015
* $Revision: 	V.1.4.5
*
* Project: 	    CMSIS DSP Library
* Title:	    arm_cfft_radix2_q31.c
*
* Description:	Radix-2 Decimation in Frequency CFFT & CIFFT Fixed point processing function
*
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*   - Redistributions of source code must retain the above copyright
*     notice, this list of conditions and the following disclaimer.
*   - Redistributions in binary form must reproduce the above copyright
*     notice, this list of conditions and the following disclaimer in
*     the documentation and/or other materials provided with the
*     distribution.
*   - Neither the name of ARM LIMITED nor the names of its contributors
*     may be used to endorse or promote products derived from this
*     software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
* -------------------------------------------------------------------- */

#include "arm_math.h"

void arm_radix2_butterfly_q31(
    q31_t *pSrc,
    uint32_t fftLen,
    q31_t *pCoef,
    uint16_t twidCoefModifier);

void arm_radix2_butterfly_inverse_q31(
    q31_t *pSrc,
    uint32_t fftLen,
    q31_t *pCoef,
    uint16_t twidCoefModifier);

void arm_bitreversal_q31(
    q31_t *pSrc,
    uint32_t fftLen,
    uint16_t bitRevFactor,
    uint16_t *pBitRevTab);

/**
* @ingroup groupTransforms
*/

/**
* @addtogroup ComplexFFT
* @{
*/

/**
* @details
* @brief Processing function for the fixed-point CFFT/CIFFT.
* @deprecated Do not use this function.  It has been superseded by \ref arm_cfft_q31 and will be removed
* @param[in]      *S    points to an instance of the fixed-point CFFT/CIFFT structure.
* @param[in, out] *pSrc points to the complex data buffer of size <code>2*fftLen</code>. Processing occurs in-place.
* @return none.
*/

void arm_cfft_radix2_q31(
    const arm_cfft_radix2_instance_q31 *S,
    q31_t *pSrc)
{

    if(S->ifftFlag == 1u)
    {
        arm_radix2_butterfly_inverse_q31(pSrc, S->fftLen,
                                         S->pTwiddle, S->twidCoefModifier);
    }
    else
    {
        arm_radix2_butterfly_q31(pSrc, S->fftLen,
                                 S->pTwiddle, S->twidCoefModifier);
    }

    arm_bitreversal_q31(pSrc, S->fftLen, S->bitRevFactor, S->pBitRevTable);
}

/**
* @} end of ComplexFFT group
*/

void arm_radix2_butterfly_q31(
    q31_t *pSrc,
    uint32_t fftLen,
    q31_t *pCoef,
    uint16_t twidCoefModifier)
{

    unsigned i, j, k, l, m;
    unsigned n1, n2, ia;
    q31_t xt, yt, cosVal, sinVal;
    q31_t p0, p1;

    //N = fftLen;
    n2 = fftLen;

    n1 = n2;
    n2 = n2 >> 1;
    ia = 0;

    // loop for groups
    for (i = 0; i < n2; i++)
    {
        cosVal = pCoef[ia * 2];
        sinVal = pCoef[(ia * 2) + 1];
        ia = ia + twidCoefModifier;

        l = i + n2;
        xt = (pSrc[2 * i] >> 1u) - (pSrc[2 * l] >> 1u);
        pSrc[2 * i] = ((pSrc[2 * i] >> 1u) + (pSrc[2 * l] >> 1u)) >> 1u;

        yt = (pSrc[2 * i + 1] >> 1u) - (pSrc[2 * l + 1] >> 1u);
        pSrc[2 * i + 1] =
            ((pSrc[2 * l + 1] >> 1u) + (pSrc[2 * i + 1] >> 1u)) >> 1u;

        mult_32x32_keep32_R(p0, xt, cosVal);
        mult_32x32_keep32_R(p1, yt, cosVal);
        multAcc_32x32_keep32_R(p0, yt, sinVal);
        multSub_32x32_keep32_R(p1, xt, sinVal);

        pSrc[2u * l] = p0;
        pSrc[2u * l + 1u] = p1;

    }                             // groups loop end

    twidCoefModifier <<= 1u;

    // loop for stage
    for (k = fftLen / 2; k > 2; k = k >> 1)
    {
        n1 = n2;
        n2 = n2 >> 1;
        ia = 0;

        // loop for groups
        for (j = 0; j < n2; j++)
        {
            cosVal = pCoef[ia * 2];
            sinVal = pCoef[(ia * 2) + 1];
            ia = ia + twidCoefModifier;

            // loop for butterfly
            i = j;
            m = fftLen / n1;
            do
            {
                l = i + n2;
                xt = pSrc[2 * i] - pSrc[2 * l];
                pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]) >> 1u;

                yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
                pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]) >> 1u;

                mult_32x32_keep32_R(p0, xt, cosVal);
                mult_32x32_keep32_R(p1, yt, cosVal);
                multAcc_32x32_keep32_R(p0, yt, sinVal);
                multSub_32x32_keep32_R(p1, xt, sinVal);

                pSrc[2u * l] = p0;
                pSrc[2u * l + 1u] = p1;
                i += n1;
                m--;
            }
            while( m > 0);                     // butterfly loop end

        }                           // groups loop end

        twidCoefModifier <<= 1u;
    }                             // stages loop end

    n1 = n2;
    n2 = n2 >> 1;
    ia = 0;

    cosVal = pCoef[ia * 2];
    sinVal = pCoef[(ia * 2) + 1];
    ia = ia + twidCoefModifier;

    // loop for butterfly
    for (i = 0; i < fftLen; i += n1)
    {
        l = i + n2;
        xt = pSrc[2 * i] - pSrc[2 * l];
        pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);

        yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
        pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);

        pSrc[2u * l] = xt;

        pSrc[2u * l + 1u] = yt;

        i += n1;
        l = i + n2;

        xt = pSrc[2 * i] - pSrc[2 * l];
        pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);

        yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
        pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);

        pSrc[2u * l] = xt;

        pSrc[2u * l + 1u] = yt;

    }                             // butterfly loop end

}


void arm_radix2_butterfly_inverse_q31(
    q31_t *pSrc,
    uint32_t fftLen,
    q31_t *pCoef,
    uint16_t twidCoefModifier)
{

    unsigned i, j, k, l;
    unsigned n1, n2, ia;
    q31_t xt, yt, cosVal, sinVal;
    q31_t p0, p1;

    //N = fftLen;
    n2 = fftLen;

    n1 = n2;
    n2 = n2 >> 1;
    ia = 0;

    // loop for groups
    for (i = 0; i < n2; i++)
    {
        cosVal = pCoef[ia * 2];
        sinVal = pCoef[(ia * 2) + 1];
        ia = ia + twidCoefModifier;

        l = i + n2;
        xt = (pSrc[2 * i] >> 1u) - (pSrc[2 * l] >> 1u);
        pSrc[2 * i] = ((pSrc[2 * i] >> 1u) + (pSrc[2 * l] >> 1u)) >> 1u;

        yt = (pSrc[2 * i + 1] >> 1u) - (pSrc[2 * l + 1] >> 1u);
        pSrc[2 * i + 1] =
            ((pSrc[2 * l + 1] >> 1u) + (pSrc[2 * i + 1] >> 1u)) >> 1u;

        mult_32x32_keep32_R(p0, xt, cosVal);
        mult_32x32_keep32_R(p1, yt, cosVal);
        multSub_32x32_keep32_R(p0, yt, sinVal);
        multAcc_32x32_keep32_R(p1, xt, sinVal);

        pSrc[2u * l] = p0;
        pSrc[2u * l + 1u] = p1;
    }                             // groups loop end

    twidCoefModifier = twidCoefModifier << 1u;

    // loop for stage
    for (k = fftLen / 2; k > 2; k = k >> 1)
    {
        n1 = n2;
        n2 = n2 >> 1;
        ia = 0;

        // loop for groups
        for (j = 0; j < n2; j++)
        {
            cosVal = pCoef[ia * 2];
            sinVal = pCoef[(ia * 2) + 1];
            ia = ia + twidCoefModifier;

            // loop for butterfly
            for (i = j; i < fftLen; i += n1)
            {
                l = i + n2;
                xt = pSrc[2 * i] - pSrc[2 * l];
                pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]) >> 1u;

                yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
                pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]) >> 1u;

                mult_32x32_keep32_R(p0, xt, cosVal);
                mult_32x32_keep32_R(p1, yt, cosVal);
                multSub_32x32_keep32_R(p0, yt, sinVal);
                multAcc_32x32_keep32_R(p1, xt, sinVal);

                pSrc[2u * l] = p0;
                pSrc[2u * l + 1u] = p1;
            }                         // butterfly loop end

        }                           // groups loop end

        twidCoefModifier = twidCoefModifier << 1u;
    }                             // stages loop end

    n1 = n2;
    n2 = n2 >> 1;
    ia = 0;

    cosVal = pCoef[ia * 2];
    sinVal = pCoef[(ia * 2) + 1];
    ia = ia + twidCoefModifier;

    // loop for butterfly
    for (i = 0; i < fftLen; i += n1)
    {
        l = i + n2;
        xt = pSrc[2 * i] - pSrc[2 * l];
        pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);

        yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
        pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);

        pSrc[2u * l] = xt;

        pSrc[2u * l + 1u] = yt;

        i += n1;
        l = i + n2;

        xt = pSrc[2 * i] - pSrc[2 * l];
        pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);

        yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
        pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);

        pSrc[2u * l] = xt;

        pSrc[2u * l + 1u] = yt;

    }                             // butterfly loop end

}
